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In Memory File System

feiben edited this page Jan 6, 2016 · 12 revisions

In real time mode, LunarMax maintains an in-memory light-weighted file system for quick access of data, avoiding most of the random disk access. Apparently, Real time mode consumes more memory than normal mode. Since on rt mode, LunarMax allocate memory by its internal lmalloc, a thing quite similar to the Linux default implemented malloc.

Of course data in memory is compressed, but if there are no sufficient memory to use, lmalloc uses external disk space for data swapping. In this situation, the performance will be slow down, so please make sure you have enough memory space for this mode. We have an estimation of consumption for you:

one property, e.g. int:payment, and each record has size limitation up to 32 KB:  
1M records (with size up to 32GB) needs about 70M memory space  
10M records (with size up to 320GB) needs about 700M memory space  
100M reords (with size up to 3200GB) needs about 7000M memory space  
...

More properties definitely needs more memory space, but linearly. You shall prepare a server with 100GB memory if you will have billions of records to compute in real time.

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